Methods and systems for performing patient or subject testing using presentation of visual stimuli or test patterns on a screen or display device are well known in the art. For example U.S. Pat. No. 6,656,131 to Alster et al., Published International Patent Application, Publication Number WO/2003/070089 and Published International Patent Application Publication Number WO/2004/098447, All of which are incorporated herein by reference in their entirety, disclose systems and methods for detecting and diagnosing eye disease by displaying visual stimuli to a subject and recording and analyzing the subject's responses. Often, such systems employ a touch sensitive screen (touch screen). Visual stimuli are presented to the subject on the touch screen. The subject may provide a response to a presented test stimulus by touching the touch sensitive screen.
In some of the above exemplary systems, the response of the subject to the presentation of a visual stimulus may be of two types. The subject may ignore the current stimulus and wait for the next stimulus, or the subject may touch the screen at a location that depends on the stimulus type, and then wait for the next stimulus. Two problems may arise with this type of task: (1) Immediately before and during the time that the stimulus is presented on the touch screen, the subject's hand must not obstruct the subject's view of the touch screen. (2) While the subject is responding, the program that displays the visual stimulus on the touch screen must delay the presentation of the next visual stimulus until the subject completes the task (i.e., touches the screen and repositions his hand such that it does not obstruct his view of the screen), before a new stimulus can be triggered.
FIGS. 1A-1E are schematic diagrams illustrating part of an exemplary prior art system employing a touch screen task presented to a subject within a test and an exemplary sequence of steps occurring within such a test. In FIG. 1A, typically, one of the subject's hands is used to perform the task (it is noted that for the sake of clarity of illustration only the hand and the eye of the subject are illustrated in FIGS. 1A-1E). The subject's hand used for performing the task is referred to as the marking hand 100 hereinafter. When the test is performed, the marking hand 100 is at rest, and the subject's eye 105 is observing a touch screen 110, while the subject is waiting for a visual stimulus to be displayed on the touch screen 110. The touch screen 110 is suitably coupled to a computer 115. The marking hand 100 may hold a stylus pen 120 for facilitating precise pointing to a specific location on the touch screen 110. At the time immediately before and during the presentation of a test stimulus on the touch screen 110, it is required that no obstacle obstructs the visual field 125 that extends from the tested eye 105 to the touch screen 110 (as schematically illustrated by the dotted lines in FIG. 1A). In FIG. 1B, a program that runs on the computer 115 displays a visual stimulus 130 on the touch screen 110, and from this time onward the program waits for the subject to respond to the presentation of the visual stimulus 130. If the subject chooses to ignore the stimulus 130 (FIG. 1C), after a predefined time, the program enables a new cycle, and the presentation of a new visual stimulus is triggered. If the subject chooses to respond to the stimulus 130 (as illustrated in FIG. 1D), the subject touches the touch screen 110 with the stylus pen 120. At this time the marking hand 100 is raised, and this may obstruct the visual field 125 of the subject. Thus it may be advantageous that the program does not present the next stimulus to the subject until the marking hand 100 is lowered such that its does not obstruct the visual field 125 of the subject, as illustrated in FIG. 1C and FIG. 1E.
Thus, there is a need for providing the system and the program controlling the operation of the system with information regarding the position of the subject's hand, as well as with information indicating whether the subject is responding to the presentation of the stimulus.